Field of the Invention
The present invention relates generally to the field of balancing loads on a suspension axle and specifically to a suspension axle for farm equipment.
Description of the Background Art
In various industry types (e.g., agricultural, transportation, manufacturing, etc.), various types of equipment can use a suspension axle to carry one or more loads (e.g., a vehicle load). One example of a suspension axle is a cantilevered rubber torsion axle 100 that is a square shaft captured inside a square tube, such as illustrated in FIG. 1. This is a common suspension axle used for farm equipment such as for a combine head trailer or seed tender. In this design, an inner 108 bar is indexed at 45 degrees with respect to an outer tube 106 and rubber chords 110 are inserted in the space between the inner bar 108 and the outer tube 106. As the inner bar 108 rotates, it compresses the rubber chords 110 which results in the suspension. Suspension arm 102 is cantilevered and is coupled to mounting bracket 104. The inner bar 108 has a front to rear arm 102 that contains the inner bar 108 at one end and a tire/hub/spindle on the opposing end, thus creating a cantilevered arm 102 on the inner bar 108.
Such existing suspension axles have a number of inadequacies, based on the configuration of the suspension axle and the spindle or suspension arms being cantilevered. For example, camber and toe varies through the stroke of the suspension arm as the suspension arm goes from unloaded to loaded to full deflection. This is in part because of the cantilevered design allowing the front to rear member to twist in the inner bar that is mounted on rubber. The only thing that keeps the inner bar and the mounting tube components together is friction. Thus, a suspension failure may result in the spindle/suspension arm separating from the mounting. That is, if the suspension member fails the axle itself will fail. Also, as the suspension member is usually made out of rubber, the rubber component can get brittle and wear out over time. If this occurs, then the entire axle must be replaced as there are no serviceable components. Mounting members are typically welded to the axle beam in this design, and so cannot be interchanged or adapted to different installation requirements. Furthermore, the suspension rate or the frame height cannot be adjusted and the members that mount an axle to the frame are also not interchangeable.
Other existing suspension axles for farm equipment also rely on cantilevered members and share many of the disadvantages of the cantilevered rubber torsion axle 100.
Thus, a suspension axle design is needed to overcome the shortcomings of currently available products.